Pineal parenchymal Tumours form from parenchymal cells or pinocytes, the cells that make up most of the pineal gland. These differ from pineal astrocytic Tumours, which are astrocytomas that form in tissue that supports the pineal gland. Grades of pineal parenchymal Tumours include the following:

Pineocytomas (grade II): Pineocytomas are slow-growing pineal Tumours that occur most often in adults aged 25 to 35.

Pineoblastomas (grade IV): Pineoblastomas are rare and highly malignant. They usually occur in children.